There have been a number of radiation detectors proposed in the prior art. U.S. Pat. No. 2,694,152 describes a detector which comprises a Geiger-Mueller counter positioned adjacent solid luminophor for detecting scintillations resulting from interaction between the radiation and the luminophor. In one embodiment the detector is positioned within a cylindrical surrounding luminophor material. U.S. Pat. No. 2,721,943 describes a detector which comprises a liquid luminophor with a light detector immersed in the liquid. U.S. Pat. No. 2,759,107 describes a scintillometer which includes a photomultiplier partly immersed in a gaseous luminophor. U.S. Pat. No. 3,139,527 describes a scintillation detector in which a scintillation crystal is disposed adjacent the face of a photomultiplier tube whereby light from the luminophor impinges upon the cathode of the photomultiplier.
The assignee of the present invention has manufactured scintillation detectors comprising a solid luminophor with a photomultiplier tube having its face abuting one surface of the luminophor to receive light generated in the luminophor by impinging radiation. Such a scintillation detector is schematically shown in FIG. 1. It includes a luminophor 11 having polished outer surfaces 12 covered by light reflective opaque material 13 such as thin aluminum foil or mylar coated with an aluminum reflecting film. The metal film is of such thickness that it blocks light, however, allows radiation such as gamma rays and beta particles to penetrate and strike the luminophor and excite scintillations. The covering film 13 includes an opening 14 through which light from scintillations can emerge and strike the face of a multiplier tube 16 which is supported (not shown) with its face against the surface of the luminophor to receive the light and provide an amplified output signal.
A major problem with the prior art detectors is that they are expensive to manufacturer because of the need for securely supporting and physically protecting the photomultiplier tube and to maintain it in contact with the face. As a result, the detector assembly is generally large and cumbersome. Multiple detectors can only be stacked in side-by-side relationship because the photomultiplier tubes extend from the side of the luminophor. The scintillation light is not efficiently collected.